Dyeing cellulosic material with naphthotriazo-disulfostilbene azoacylacetarylide sulfonic acids



United States Patent M DYEING CELLULOSIC MATERIAL WITH NAPH- THQTRIAZO DISULFOSTILBENE AZOACYLA- CETARYLIDE SULFONIC ACIDS Alvin C. Litke, Buffalo, N.Y., assignor to Allied Chemical gorporation, New York, N.Y., a corporation of New ork No Drawing. Filed Sept. 4, 1964, Ser. No. 394,593 12 Claims. (Cl. 8-7) This application is in part a continuation of my copending application Serial No. 75,106 filed December 12, 1960.

This invention relates to the coloring of cellulosic materials. It relates more particularly to the dyeing of cellulosic materials and especially paper with a novel class of monoazo dyestuffs containing a triazine nucleus and to the resulting dyed products. I

An object of the present invention is to provide improvements in cellulosic materials and especially paper which are colored greenish-yellow to reddish-yellow hues which are fast to light and which are particularly distinguished by their dischargeability by common bleaching agents.

An additional object of the present invention is to provide dyeings on paper which are characterized by their bright greenish-yellow hues, by their relative fastness to light but fading directly on tone (that is, the color of the paper becomes weaker but does not change in hue on fading), by their substantial freedom from twosidedness (that is, the color of the top side and the bottom or screen side of the paper is substantially the same), and by their dischargeability by common bleaching agents.

Other objects of the invention in part will be obvious and in part will appear hereinafter.

According to the present invention, cellulosic materials and especially paper are colored bright greenish-yellow to reddish-yellow hues which are characterized by the above advantageous properties, by contacting the cellulosic material, and especially fibrous cellulosic material such as cellulosic textile materials and paper, with a monoazo dyestuff, or mixture of monoazo dyestuffs, which in the free acid form are 4-[4'-(l",2-naphthotriazo)-2,2- disulfostil'benelazo-acylacetarylide :sulfonic acids free from chromophoric substituents and having a maximum of four sulfonic acid groups. Such monoazo dyestuffs are disclosed and claimed in my said copending application Serial No. 75,106, filed December 12, 1960.

I have discovered that the said monoazo dyestuffs constitute advantageous coloring agents for the production of colored, and especially dyed, cellulosic materials and particularly paper. Thus, they possess a very good aflinity for cellulosic fibers so that upon addition to cellulosic materials they generally yield pure, greenish-yellow to reddish-yellow hues having good fastness to wet processing and to light. The dyeings obtained on cellulosic mater-ia'ls and especially paper with said dyestuffs are distinguished by the brilliance of their yellow color when exposed to ultra-violet radiation and by their surprising and extremely desirable characteristics of fading directly on tone and of being dischargeable by the common bleaching agents. In addition, the dyeings on paper are characterized 'by being substantially free from two-sidedness.

The invention is particularly important in connection with the dyeing of paper, since it makes possible the provision of dyed papers having pure greenish-yellow to reddish-yellow hues which are substantially free from two-sidedness, which possess good fastness to wet processing and to light and which fade directly on tone when they do fade, and which can be substantially completely bleached by the common bleaching agents, such as hypochlorite. Freedom from two-sidedness is an 3,238,009 Patented Mar. 1, 1966 important advantage, since many dyestuffs give stronger dyeings on the top side of the paper, and weaker dyeings on the bottom or screen side, because of their unequal affinity for long and short fibers in the paper making machine. Bleachability is of particular importance, since wastes from colored paper manufacture can be completely discolored, thereby rendering the waste paper capa'ble of reuse and permitting wastes of papers of several different colors to be combined and reused. An obvious economic advantage can be derived from the recovery of such waste paper stock.

The dyestuffs employed in accordance with the present invention have the general formula R represents a naphthalene radical fused to the triazole ring in the ll-positions, as indicated by the valence bonds,

R is an alkyl or aryl radical,

R is an aryl radical,

M is a cation,

and the total number of sulfonic acid groups in the dyestuff does not exceed four.

They include compounds in which the naphthalene radical (represented by R in the above formula) and the aryl nuclei of the .acylacetarylide component (represented by R and R in the above formula) may contain one or more non-chromophoric substituents, including members selected from the group consisting of hydroxy, halogen, lower (i.e., one to eight carbon atoms) alkyl, lower alkoxy, carboxylic acid and its salts and functional derivatives (e.g., esters, amides, and nitrile), and sulfonic acid and its salts and functional derivatives (e.g., esters, amides and sulfones). Those in which the napthotriazine nucleus contains at least one, and especially tw-o, sulfonic acid substituents are preferred in view of their superior dyeing characteristics.

For use in accordance with the present invention those dyestuffs are preferred of which the cation (represented by M in the above formula) is such as to provide a solubility in water to the extent of at least 1 part in 200 parts by weight of water. Especially preferred are those dyestuffs in which M is an alkali metal or an ammonium cation and particularly sodium, which permits addition of the dyestuif to the papermaking process or other dyeing process in the dry or dissolved form, in the winter as well as summer.

The coloring, and particularly the dyeing, of cellulosic materials and especially cellulosic fiber can be carried out by any of the methods heretofore known for the application of monoazo dyestuffs of said class to cellulosic materials. No special dyeing technique is required for the successful application of the dyestuffs to said material.

Thus, they can be applied by the various methods heretofore described as useful or normally used for the dyeing and printing of cellulosic fibrous material, and especially paper, with monoazo dyestuffs and particularly tilt; water-soluble monoazo dyestuffs classified as direct co ors.

The dyestuffs employed in the practice of this invention can be produced by diazotizing an aminonapthotriazostilbene of the general formula NN C II: C II NIIz n is an integer not greater than 6. and coupling the resultant diazonium salt in an alkaline medium with an acylacetarylide of the general formula E (III) wherein R and R have the above meanings. The resulting dyestuff precipitates from solution, and is separated, e.g. by filtration, from the mother liquor.

The aminonaphthotriazostilbenes which correspond to the above general Formula II may be prepared in any known manner. For example, 4-amino-4-nitrostilbene- 2,2'-disulphonic acid is diazotized and coupled with an aminonaphthalene molecule which is capable of coupling in a position ortho to the amino group; the resulting ortho amino azo coupling product is treated with an oxidizing agent, e.g., sodium hypochlorite, copper salts, chlorine and the like, to produce the corresponding nitronaphthotriazostilbene; and the nitro group of this product is then reduced to the amine, for example, by treatment with a reducing agent such as iron, zinc or Nags.

The coupling reaction between the diazotized aminostilbene and the naphthylamine is best carried out in a mildly acidic medium at a pH of about 4 to about 6.8. Acidic conditions such as these favor coupling in the desired ortho position to the amino group of the naphthylamine.

Oxidation of the ortho amino-azonapthalene to the corresponding triazine can be accomplished with a variety of mild oxidizing agents. Formation of the triazine ring is preferably effected by means of ammoniacal solutions of copper salts, e.g., ammoniacal cupric sulfate. In addition, alkaline hypohalite solutions such as, sodium, hypochlorite and sodium hypobromite can be used. The following are typical examples of a large number of aminonapthalenes which have been converted in this mannet to the corresponding 4-amino-4'-(1,2"napthotriazostilbene)-2,2-disulfonic acid:

2-naphthylamine l-naphthylamine-4-sulfonic acid 2-naphthylamine-S-sulfonic acid Z-naphthylarnine-6-sulfonic acid 2-napthylamine-7-sulfonic acid 2-naphthylamine-3,6-disulfonic acid 2-naphthylamine-5,7-disulfonic acid 2-naphthylamine-6,8-disulfonic acid 1-amino-4-ethoxynapthalene Z-amino-3-amoxynaphthalene 2-amino-6-isobutylnaphthalene Various acylacetarylides which correspond to the above general Formula III can be coupled with the diazotized 4-amino-4' 1",2"-naphthotriazostilbene) 2,2'-disulfonic acid. Preferably, the aryl nucleus represented by R in the above general Formula 111 is a phenyl group and contains at least one additional substituent such as an alkyl, alkoxy, halogen, .trifiuoromethyl nitrile, or sulfonic acid group. Of especial value are those acylacetanilides containing an alkoxy group in the ortho position to the amide group.

The following acylacetarylides are typical examples of this class of coupling components:

Acetoacetylaminobenzene 4-acetoacetylaminobenzenesulfonic acid Acetoacetyl-2-aminonaphthalene Z-ethoxyl-acetoacetylaminobenzene 4-methoxy-1-acetoacetylaminobenzene 2-ethoxy-4-trifluoromethyl- 1-acetoacetylaminobenzene 2-methoxy-5-ethyll-acetoacetylaminobenzene Z-cyanol-acetoacetylaminobenzene 2-bromo-6-methyll -acetoacetylaminobenzene 2,4-dimethyll -acetoacetylaminobenzene 2-ethoxy-4-bromo-S-methyl-1-acetoacetylarninobenzene 2-ethoxy-4-chloro-6-methyl-1-acetoacetylaminobenzene 2-rnethoxy-6-trifluoromethyl-1-acetoacetylaminobenzene 2-ethoxy-4-tritiuoromethyl-1-acetoacetylaminobenzene Benzoylacetylaminobenzene In a preferred mode of carrying out the preparation of the said dyestuffs, equimolecular proportions of diazotized 4-amino-4'-nitrostilbene-2,2-disulfonic acid and a naphthylamine sulfonic acid, e.g., 2-aminonaphthalene- 3,6-disulfonic acid, are coupled in a weakly acid medium. The coupling mass is heated to about 70 C., and is then made alkaline to Brilliant Yellow test paper with an inorganic alkali, e.g., soda ash, potassium hydroxide or trisodium phosphate. The aminoazo product is isolated by salting it out of solution, and then filtering the precipitate from the mother liquor.

The isolated aminoazo compound is slurried in hot water and an ammoniacal solution of a copper salt is added. The mixture is boiled under refluxing conditions for about 24 hours, filtered to remove insoluble material, and isolated by the addition of salt and then cooling.

The filtered naphthotriazine product is reslurried in hot, dilute, aqueous mineral acid and the nitro group is reduced to the amine, e.g., by the addition of iron and zinc. The aminostilbenetriazine product is isolated by neutralizing the reduction reaction mixture, salting out, and filtering.

The isolated product is slurried in water and then diazotized in the conventional manner. The dlazonium salt is coupled in a strongly alkaline medium (alkaline to Brilliant Yellow paper) with an acylacetarylide, preferably one bearing a lower alkoxy group in the ortho position of the aryl nucleus, e.g., 2-methoxy-l-acetoacetylaminobenzene. When the coupling is completed, usually after 10 to 24 hours, the product is salted out and isolated in a conventional manner.

The dyestuff is thus obtained in the form of its sodium salt, which is preferred. It can be converted to its free acid form by dissolving the sodium salt in water and adding an acid, e.g., sulfuric acid, hydrochloric acid, formic acid, until the mixture reacts distinctly acid. Thereafter evaporation of the mass to dryness yields the dyestutf in the free acid form. Similarly the dyestuff can be obtained in the form of other salts, e.g., salts of other metals such as potassium, calcium, manganese, magnesium, aluminum, chromium or organic amine salts such as those derived from dioctyl amine, guanidine, amino morpholine, by dissolving the sodium salt in hot water, acidifying the solution and adding at least the stoichiometric amount, but preferably an excess of a soluble salt of the desired metal or organic amine. Thereafter the mixture is cooled to precipitate the salt, if insoluble, or the mass can be evaporated to dryness.

The dyestutf also can be obtained in the free acid form by suspending the sodium salt form thereof in an organic solvent, e.g., methylene chloride, or acetone, and bubbling gaseous hydrochloric acid into the suspension to liberate the free acid form of the dyestutf, which dissolves in the solvent and can be separated by filtration from the sodium chloride which also forms. The solvent solution of the free acid can be used directly or evaporated to dryness to obtain the free acid in solid form. Alternatively, the solvent solution can be admixed with an amine, and the illustrate the present invention.

resultant amine salt can be obtained by evaporation of the solvent. Other methods of obtaining various inorganic and organic salts of these dyestuffs will be obvious to those skilled in this art.

Preferred naphthotriazostilbene dyestuffs thus obtained for use in the practice of the present invention are generally light yellow powders which are easily soluble in R is a member selected from the group consisting of methyl and phenyl,

R is a member selected from the group consisting of the benzene radical, the naphthalene radical, and substituted benzene radicals containing one to three substituents selected from the group consisting of lower alkyl, lower alkoxy, trifiuoroalkyl, nitrile, halogen and $0 M,

X is a substituent selected from the group consisting of hydrogen, halogen, lower alkyl, lower alkoxy and SO M,

n is an integer from 1 to 6, and

M is a cation,

said dyestuff having a maximum of four SO M groups. The following specific Examples A-G illustrate the preparation of the dyestuffs, and specific Examples 1-6 The temperatures are given in degrees centigrade and the parts and percentages are by weight, unless designated as parts by volume. In the latter instance, the amount signifies the volume occupied by the same number of parts by weight of water at 4 C. It will be understood, however, that the invention is not limited to the details set out therein and that changes can be made without departing from the scope of the invention.

Example A The sodium salt of 4-amino-4-nitrostilbene-2,2'-disulfonic acid (44.4 parts) was diazotized in the conventional manner, and the diazonium salt was coupled in a weakly acidic medium at pH 5.5, with 2-arnino-naphthalene-3,6- disulfonic acid (30.3 parts).

The mixture was agitated until the disappearance of the diazonium salt indicated completion of the coupling reaction. The mass was then heated to 70, and sufiicient sodium carbonate was added to render the solution alkaline to Brilliant Yellow test paper. Sodium chloride was added to cause the monoazo product to begin to precipitate, and the mixture was then cooled to below ambient temperature. The resultant slurry was filtered.

The filter cake was reslurried in 100 parts of water and the slurry was heated to solution at 90. To this hot solution was added a solution prepared from 50 parts of copper sulfate pentahydrate, 66.5 parts of 28 percent aqua ammonia and 200 parts of water. The resultant mixture was heated to boiling, and boiled under reflux for a maximum of 24 hours. The mass was filtered, the residue discarded, and the clarified filtrate was salted, cooled and filtered again.

The filter cake of 4-nitro-4'-(1,2"-naphthotriazostilbene)-2,2',3",6"-tetrasulfonic acid thus obtained was reslurried in 1500 parts of water, and 34.8 parts of 20 B. hydrochloric acid were then added. The mixture was heated to 98100, and 40 parts of iron powder (60 mesh) were then added as rapidly as the foaming of the mixture would permit. The reduction mixture was heated at just below boiling for two hours, rendered alkaline to Brilliant Yellow test paper by the addition of sodium carbonate, and then filtered to remove insoluble material. The clarified filtrate was salted, cooled and filtered.

The filter cake of 4-amino-4'-(l",2"-naphthotriazostilbene)-2,2',3",6"-tetrasulfonic acid was reslurried in 500 parts of water. After the addition of 29 parts of 20 B. hydrochloric acid, sufiicient ice was added to cool the mixture to 10". An aqueous solution of sodium nitrite was added to the mass during two hours, and the mixture was agitated until no free nitrous acid could be detected. The resultant diazonium salt solution was added to a mixture consisting of 22 parts of Z-methoxyl-acetoacetylaminobenzene, 30 parts of sodium carbonate and 300 parts of water which had been cooled to 5 The coupling mass was agitated without further temperature control for 24 hours. The resultant monoazo dyestuff 4- [4'-( l",2"-naphthotriazo)-2,2'-disulfostilbene] am- (2" methoxy)aceto'acetanilide-3,6"-disulfonate, which in the free acid form has the formula O=CNH N 50311 SlOa 01130- HOaS SOaH precipitated from the coupling solution and was isolated by filtration and dried. The resulting dyestuif is a yellow powder.

Example B In an analogous manner to that described above, 4- amino-4-(l",2"-naphthotriazostilbene) 2,2',6" trisulf-onic acid was diazotized and coupled into Z-methoxy-lacetoacetylaminobenzene. The resulting product, 4-[4'- (l",2-napthotriazo)-2,2-disulfostilbene] azo-(2"' methoxy)acetoacetanilide-6"-sulfonate, in the free acid form has the formula SOaH Example C In a similar manner to that described in Example A above, Z-amino8-methoxynaphthalene-6 sulfonic acid was converted into 4-amino-4-(8"-methoxy-1",2-naphthotriazostilbene)-2,2'-6"-trisulfonic acid of the formula OaH (VII) This product was diazotized and coupled into Z-methoxy-l acetoacetylaminobenzene to produce the dyestuff, 4-[4-(1",2-naphthotriazo) 2,2 disulfostilbene1azo- (2"'-methoxy)acetoacetanilide-6"-sulfonate, of the formula (in the free acid form) (VIII) CHaO Examples D to G The procedure of Example A is followed in preparing several other similar dyestuffs, the components of which Example 3 A dyebath was prepared by adding 0.5 part of the dyestufi produced as described in Example A above to 500 parts of water, and agitating the mixture until complete solution had occurred. White bond paper was dyed by immersing it in the resulting solution and maintaining the temperature at about 70 for to minutes, rinsing are set out in Table I. 15 with cold water, and drying in the air. The paper was TABLE I Aminonaphthalene component Example used to prepare Acetoaeetylaryllde coupling component napthotrlazostilbene IIIH; 0 CHgOH;

I] H D CHaCCHzCN OH CI 0 CHzCH: t i E NH: CHaC-CHy-C-fi' SOsH SO3H CN 0 CH; 11 E] F... HOaS NH; CHsCCH C-H I] ll G NH2 CHr-C-CHaCH CF;

SOaH

Example 1 A. Paper dyeing-A stock solution of the dyestufl? produced as described in Example A above was prepared by adding 0.750 parts of the dye to 500 parts of boiling water, and boiling and agitating the mixture until complete solution had occurred.

Ten parts of this stock solution were agitated for 10 minutes with 250 parts (by volume) of bleached sulfite pulp containing 3 parts of pulp (dry weight). Thereafter 4 parts (by volume) of 3 percent starch solution, and a like amount of 10 percent alum solution were added. The mixture was agitated for minutes, diluted to 2000 parts (by volume) by the addition of water, and finished into paper in a conventional manner. The paper was dyed a bright greenish yellow which fluoresced strongly when exposed to ultra-violet radiation.

B. Bleachability test.Strips 11" x 4"), of paper prepared as above, were immersed into a ml. graduated cylinder containing an aqueous 5.25 percent sodium hy pochlorite solution. After 10 minutes, the bleached strips were removed and dried in air. The color was completely discharged from the strips indicating the susceptibility of the dyestutf to the discoloring action of bleaching agents.

Example 2 Dyed paper was produced in the manner described dyed a bright greenish-yellow which fluoresced strongly when exposed to ultraviolet radiation. When subjected to bleaching in the manner set out in above Example 1, Part B, the color was completely discharged.

Example 4 Example 5 A stock solution of the dyestutf produced as described in above Example C was prepared as described in above Example 1 and employed to produce dyed paper, as described in said example. The resulting paper was dyed a redder yellow hue that that of Examples 1 and 4. When exposed to ultraviolet radiation it fluoresced brilliantly. The color was removed by bleaching in the manner described in Example 1, Part B.

Example 6 Cotton dyeing.A dyebath was prepared by dissolving 2 parts of the dyestuff produced as described in above Example A in 500 parts of boiling distilled water, and adding 100 parts by volume of the resultant solution to a mixture of 30 parts by volume of 20% aqueous sodium chloride and 270 parts of Water. A skein of cotton yarn weighing 200 parts is immersed in the resulting dyebalth and the bath is heated to and maintained at the boil for 45 minutes, with intermittent working of the skein in the bath. The bath is permitted to cool for 15 minutes and the skein is removed, rinsed in cool water and dried. The cotton yarn is dyed a bright greenish yellow having excellent dischargeability.

While the above describes the preferred embodiments of the invention, it will be understood that departures may be made therefrom within the scope of the specification and claims.

I claim:

1. A cellulosic material colored with a monoazo dyestufi which in the free acid form is a 4 [4' (1",2"- naphthotriazo) 2,2 disulfostilbene]azoacetoacetanilide sulfonic acid having a lower alkoxy group as sole additional substituent in the anilide radical, and having a maximum of four sulfonic acid groups, at least one of which is in the napthotriazine radical, said naphthotriazine radical being free from further substituents.

2. A cellulosic material dyed with a monoazo dyestuff of the formula R is a member selected from the group consisting of methyl and phenyl,

R is a member selected from the group consisting of the benzene radical, the naphthalene radical, and substituted benzene radicals containing one to three substituents. selected from the group consisting of lower alkyl, lower alkoxy, trifluoroalkyl, nitrile, halogen and --SO M,

X is a substituent selected from the group consisting of hydrogen, halogen, lower alkyl, lower alkoxy and SO M,

n is an integer from 1 to 6, and

M is a cation,

said dyestutf having a maximum of four S M groups.

3. A cellulosic material dyed with a monoazo dyestufi which in the free acid form is 4 [4 (1",2 naphthoitriazo) 2,2 disulf ostilbene]azoacetoacetanilide sulfonic acid having a lower alkoxy group as sole additional substituent, in the anilide radical, and having a maximum of four sulfonic acid groups.

4. A paper dyed with a monoazo dyestufl? as defined in claim 2.

5. A paper dyed with a monoazo dyestuif as defined in claim 3 in which the lower alkoxy group is in ortho position to the amide group.

6. A paper dyed with a sodium salt of a monoazo dyestuff as defined in claim 5 in which one of the sulfonic acid groups is in the 6-position of the naphthotriazine radical.

7. A paper dyed with a monoazo dyestuif as defined in claim 1 in the form of its sodium salt.

10 8. A paper dyed with the monoazo dyestuff having in the free acid form the formula 9. A paper dyed with the monoazo dyestufi having in the free acid form the formula HOaS 10. A paper dyed with the monoazo dyestutf having in the free acid form the formula 11. A paper dyed with the monoazo dyestufi having in the free acid form the formula 12. A paper dyed with the monoazo dyestuff having in the free acid form the formula OTHER REFERENCES Lubs, The Chemistry of Dyes and Synthetic Pigments, page 663, pub. by Reinhold Publ. Corp., 1955.

Review of Textile Progress, 1961, pages 240-141, pub. 1962 by Butterworth Inc., Washington, DC

NORMAN G. TORCHIN, Primary Examiner. 

1. A CELLULOSIC MATERIAL COLORED WITH A MONOAZO DYESTUFF WHICH IN THE FREE ACID FORM IS A 4-(4''-(1",2"NAPHTHOTRIAZO) -2,2''- DISULFOSTILBENE)AZOACETOACETANILIDE SULFONIC ACID HAVING A LOWER ALKOXY GROUP AS SOLE ADDITIONAL SUBSTITUENT IN THE ANILIDE RADICAL, AND HAVING A MAXIMUM OF FOUR SULFONIC ACID GROUPS, AT LEAST ONE OF WHICH IS IN THE NAPTHOTRIAZINE RADICAL, SAID NAPHTHOTRIAZINE RADICAL BEING FREE FROM FURTHER SUBSTITUENTS. 